1. Field of the Invention
The present invention relates to a device for fixing a tool element such as a disc-like grinding wheel, a cutting wheel and a wire brush to a spindle of a rotary tool such as a grinder, a sander and a polisher.
2. Description of the Prior Art
A conventional fixing device includes a flange member mounted on an end portion of a spindle of a rotary tool. With a tool element abutted on the flange member, a lock nut is engaged with the spindle and is tightened to clamp the tool element between the lock nut and the flange member, so that the tool is fixed in position perpendicular to the spindle.
However, with the conventional clamp device, both the flange member and the lock nut are made of rigid material, so that vibrations of the rotary tool produced during the operation is directly transmitted to an operator. Further, noises are produced by the vibrations and are amplified during transmission. This may provide an undesirable operation feeling to the operator.
In order to solve this problem, Japanese Utility Model Publication No. 39-31638 proposes "Noise Prevention Device" in which a tool element is clamped between a flange member and a lock nut with resilient members interposed between the flange member and the tool element and between the lock nut and the tool element, respectively. With this construction, vibrations of the tool element are absorbed by the resilient member, so that the vibrations transmitted to an operator are reduced and so that its accompanying production of noises is lowered. Thus, the operation feeling of a rotary tool is improved.
On the other hand, when the tool element is clamped between the rigid flange and the rigid lock nut with the center of the tool element being displaced from the center of the spindle, there arises a problem that the tool element bounds against a work and that such a bounding movement is transmitted to the hands of the operator when the tool element is rotated and pressed on the work. With the device of the above publication, since the tool element is movable to some extent in a direction perpendicular to the spindle, the displacement of the center of the tool element may be automatically absorbed, so that the bounding movement can be reduced. Thus, the operation feeling of the rotary tool is improved by the device of the above publication also in this point.
However, with the device of the above publication, since the tool element directly contacts the resilient member, the resilient member tends to be abraded when the tool element is mounted on or removed from the rotary tool. Therefore, the device has a low durability.